Hyponatremic hypertensive syndrome is a manifestation of severe hypertension related to renal ischemia. The most common underlying cause of hyponatremic hypertensive syndrome in adults is severe atherosclerotic reno-vascular disorder while in children the most common cause of hyponatremic hypertensive syndrome is unilateral congenital renal artery stenosis due to some form of arterial dysplasia. An excessively stimulated renin-angiotensin-aldosterone system is mainly responsible for heavy polyuria, renal electrolyte loss and proteinuria. The neurological manifestations of hyponatremia and/or hypertensive encephalopathy are the main presenting symptoms, and they are not always in linear correlation with the degree of hyponatremia and/or hypertension. The cornerstone of management is the treatment of underlying hypertensive disease, but the correction of hyponatremic dehydration and safe decrease of blood pressure are essential in the emergency phase of hyponatremic hypertensive syndrome. The optimal antihypertensive therapy depends on the underlying condition. Revascularization, either surgical or by percutaneous transluminal angioplasty, is recommended for children with renal artery stenosis. Pharmacological treatment based on ACEI and/or ARB is the most efficient antihypertensive therapy for those with ischemic reno-parenchymal disorder. Nephrectomy is required if an affected kidney contributes less than 10% of the global renal function, if percutaneous transluminal angioplasty fails and the operative risk is too high, or in the case of extensive tumorous lesions.